On Martian surface, a slice of Kerala: Periyar river, Varkala beach, ISRO birthplace

In all, seven Indian names feature in the latest list prepared by the IAU’s Working Group for Planetary System Nomenclature. The name of two other locations on Mars honours the renowned geologist M S Krishnan, the first Indian to become the director of the Geological Survey of India in 1951. The crater named after Krishnan measures 77 km in diameter and is believed to be over 3 billion years old. And a plain surface to the southeast of this crater, about 50 km in diameter, will be known as Krishnan Plaus.

According to the nomenclature rules for Mars, large craters, of the size 50 km or larger, are named after scientists, while smaller craters are to be named after small towns and villages anywhere in the world with populations of about 100,000 or less. “This category is simply a large source of crater names. No commemoration of specific towns or villages is intended,” the rules say.

There are more than 2,000 features on Mars that have been named until now, according to the Gazetteer of Planetary Nomenclature maintained by the US Geological Survey, one of the most authoritative databases on the subject. About 50 of them have Indian references, including names of Indian towns and villages.

For naming stars or planets or geological features on the planets, the IAU issues a ‘Call for Proposal’ seeking names from requestors worldwide. Along with the name, its origin and description of the feature needs to be submitted along with a short scientific explanation. The submission must also include the annotated and unannotated images of the feature, the feature type, latitude or longitude in the correct coordinate system, and its size, if known.

In some cases, there are country-specific groups to whom the names are first submitted after which it is sent to the IAU. In some other cases, the proposer sends the names to the IAU. The final selection is done by the highest officials of the IUA after deliberation and committee-level meetings.

In case of the latest Martian crater naming, the proposal was sent by scientists at the Indian Institute of Space Science and Technology (IIST) based on their ongoing research.

In the latest addition, the IAU has chosen a 9-km wide crater along the eastern region of the Krishnan crater to be named after Varkala. Varkala beach is one of the most visited tourist locations in Kerala. The Varkala cliff holds significance geologically — its jarosite remains offer the closest links to Martian land composition and could offer clues to Martian evolutionary history.

Valiamala is a relatively smaller crater (13.5 km diameter) to the west of the Krishnan crater. Valiamala is the home of the IIST.

A crater located to the south east of the Krishnan crater has now been named after Thumba, the birthplace of the Indian Space Research Organisation (ISRO). It was in November 1962 that Vikram Sarabhai chose this coastal town in Kerala to establish the Equatorial Rocket Launching Centre. Today, the Vikram Sarabhai Space Centre, called the backbone of ISRO, operates near Thumba.

The name Periyar has been chosen for the lone Martian valley located along the southern region of the Krishnan crater. Periyar is Kerala’s longest river, running 300 km from the Shivagiri hills in Tamil Nadu to the Arabian Sea near Cochin.

The IAU has identified a tiny, independent crater located to the east of the Krishnan crater as Bekal (4.9 km diameter). It is named after the mid-17th century fort in the northern Kerala town of the same name. Overlooking the Arabian Sea, the Bekal fort was in the hands of the Keladi Nayaka dynasty, Hyder Ali of Mysore and then the British.

Apart from these seven Indian names, the Martian surface also has geological features named after the Ganga. But these names were not proposed by India.